Thousands of guns and knives have been recycled
Guns and knives seized by the Metropolitan Police are being melted down into girders for the 2012 Olympic Games site in Stratford, east London.
The weapons are among a variety of unusual materials recycled by the force according to its environmental report.
Lead, brass and aluminium from used bullets at the Met's firing range became jewellery and photo frames.
Meanwhile the 4,000 tonnes of manure created by the Met's 120 horses gets turned into fertiliser.
Even the animals' horseshoes have been reused - all 14 tonnes of them.
The quantities were set out in the Met's annual recycling assessment.
Sarah Foster, of the Met's environmental team, said: "The Met is a huge operation across the capital, employing over 50,000 people working from almost 800 buildings.
"Our environmental policy has been really successful in minimising the potential environmental impact of what we do for London."
She continued: "We're constantly looking for new ways to recycle and new markets for our recyclable materials, to conserve resources, save energy and money."
So far thousands of guns and knives have been melted down for reuse.
More than 40 tonnes of police clothing, including Kevlar body armour, has been recycled for use in cars.
And some 20,000 litres of cooking oil from the force's canteens has become bio-diesel fuel.